Generally, a hearing function of a person is one of the most organ developed for the first time in sensory organs, and if hearing stimuli are appropriately applied to the human body, stimuli for the left brain and the right brain are accelerated to give many influences to the development of the brain and other senses such as smell and vision.
According to the researches using sounds, natural sounds contain many high-frequency sounds, and when a person hears the natural sounds, accordingly, he or she feels relaxation and generates alpha waves from his or her brain. Moreover, music is to improve a communication capability of people in the social activities and give an influence to the cognitive function of people.
Most people think noise is an element of inhibiting their work needing cognition performance ability. Conventional technologies related to white noise among various noise are disclosed in Korean Patent Application Publication No. 10-2010-00046 (entitled ‘hard disk type language learning device for concentration reinforcement’), Korean Patent Application Registration No. 10-0812770 (entitled ‘method and apparatus for providing double speed narration voice signal using white noise’, and in Korean Patent Application Publication No. 10-2011-0073404 (entitled ‘lighting device system having noise control/sound therapy function) and so forth.
The conventional technologies generate white noise to remove noise components by generating white noise or remove noise components, so that a user's concentration is improved, however, they are technologies to generate the white noise. Accordingly, they do not use the white noise to improve the concentration in work or study through the stress relaxation or the maintenance of appropriate tension by using white noise.